1. Field of the Invention
This invention relates to transient suppression circuits, and in particular to an arrangement incorporating a transient suppression circuit within an electrical connector.
2. Description of Related Art
Transient suppression circuits are required in a variety of applications for the purpose of protecting electric circuit elements from transient voltage pulses induced in connecting cables. Generally, such circuits operate by shunting the transients to ground via a circuit element responsive to the transient voltage or current, and which normally is in an "off" state to permit desired signals to pass along the protected signal line. For this purpose, it is well known to use a semiconductor diode as the shunt device.
It is also known to improve the transient suppression capability of a shunt diode by providing either a positive or a negative diode bias current. Biasing of the diode reduces its internal capacitance and therefore reduces signal distortion. Also, biasing places the diode in a partially "on" state, reducing the turn-on time for shunting transients to ground.
A possible transient suppression diode biasing circuit is shown in FIG. 1. A bias voltage for the diodes is input through terminals 1 and 2. Desired signals are input through terminals 3-22 and output through terminals 93-112. The input lines connecting terminals 3-22 and 93-112 are respectively connected to ground via negatively biased diodes 33-52 and positively biased diodes 63-82. A ground path is completed by common negatively biased diode 25 and common positively biased diode 85.
For many applications, it would be desirable to place such a transient suppression circuit directly within a cable connector. However, even though recent improvements have made it possible to place unbiased transient suppression circuits in a connector, as shown for example in U.S. Pat. No. 4,747,789, it has heretofore been impossible to place a biased transient suppression circuit in a connector.
In known transient suppression connectors, a single diode is placed directly on the connector contact, with one lead electrically connected to the contact and the other to a conductive sleeve engaged by resilient tines extending into apertures within a ground plate. The ground plate is electrically connected to the shell of the connector to complete the ground path from the contact. Examples of such connectors are shown in U.S. Pat. Nos. 4,747,789 and 4,572,600.
Due to spatial constraints, however, this type of connector has only been applied to circuits requiring a single non-biased shunt diode for each contact. Application of a biased transient suppression circuit to a transient suppression connector has not heretofore been proposed.